Marie Faruch

Geometric morphometric analysis reveals sexual dimorphism in the distal femur.

An individuals sex can be determined by the shape of their distal femur. The goal of this study was to show that differences in distal femur shape related to sexual dimorphism could be identified, visualized, and quantified using 3D geometric morphometric analysis. Geometric morphometric analysis was carried out on CT scans of the distal femur of 256 subjects living in the south of France. Ten landmarks were defined on 3D reconstructions of the distal femur. Both traditional metric and geometric morphometric analyses were carried out on these bone reconstructions; these analyses identified trends in bone shape in sex-based subgroups. Sex-related differences in shape were statistically significant. The subjects sex was correctly assigned in 77.3% of cases using geometric morphometric analysis. This study has shown that geometric morphometric analysis of the distal femur is feasible and has revealed sexual dimorphism differences in this bone segment. This reliable, accurate method could be used for virtual autopsy and be used to perform diachronic and interethnic comparisons. Moreover, this study provides updated morphometric data for a modern population in the south of France.

Historical perspective on the “discovery” of the anterolateral ligament of the knee

There is a lively debate about the existence, origins and discoverer of the anterolateral ligament of the knee. The complex anatomy of the lateral aspect of the knee has made it difficult to differentiate between various structures such as the iliotibial band, capsulo-osseous layer, Kaplan’s fibres and the anterolateral capsule. The “discovery” of a new anterolateral structure in 2013 was the culmination of many historical studies. In 1879, Paul Ferdinand Segond described a tibial plateau fracture in which he noted a pearly band reinforcing the joint capsule. Other anatomists had their suspicions about this ligament; it was described by Vallois in 1914 in his thesis and extensively studied by Jost in 1921. References to it can be found in comparative anatomy studies. This historical review serves as a reminder that understanding and treating knee sprains is not something new.Level of evidenceV.

Three-dimensional geometric morphometric analysis reveals ethnic dimorphism in the shape of the femur

BackgroundEthnic dimorphism in the distal femur has never been studied in a three-dimensional analysis focused on shape instead of size. Yet, this dimorphism has direct implications in orthopedic surgery and in anthropology. The goal of this study was to show that differences in distal femur shape related to ethnic dimorphism could be identified, visualized, and quantified using 3D geometric morphometric analysis.MethodsCT scans of the distal femur were taken from 482 patients who were free of any bone-related pathology: 240 patients were European (E) and 242 were Asian (A). Ten osteometric landmarks based on standard bone landmarks used in anthropometry were placed on these scans. Geometric morphometric analysis, principal component analysis (PCA), canonical variates analysis (CVA), and other discriminant analyses (Goodall’s F-test and Mahalanobis distance) were performed. A cross-validation analysis was carried out to determine the percentage of cases in which the ethnicity was correctly estimated.ResultsThe shape of the E and A distal femur differed significantly (Goodall’s F = 94.43, P < 0.001 and Mahalanobis D2 distance = 1.85, P < 0.001). PCA identified a difference in distal femur shape between A and E. The CVA revealed that correct ethnicity was assigned in 82% of cases and the cross-validation revealed a 75% rate of correct ethnic group estimation.ConclusionThe distal femur exhibits ethnic dimorphism. 3D geometric morphometric analysis made it possible to demonstrate these differences. The large number of subjects studied has helped modernize the references for certain bone measurements, with direct implication for orthopedic surgery and anthropology.

Hamstring Graft Incorporation According to the Length of the Graft Inside Tunnels.

Background: Anterior cruciate ligament (ACL) reconstruction with a quadrupled semitendinosus (ST4) graft is an evolution of the standard technique with 2 hamstring tendons (semitendinosus + gracilis [STG]). However, there is no published comparison of how well these 2 types of hamstring grafts are incorporated into the bone tunnels. Because the ST4 graft is shorter, there is less graft material inside the tunnels. Purpose: To use magnetic resonance imaging (MRI) to compare graft incorporation in the tibial bone tunnels 1 year after ACL reconstruction with either an STG graft or ST4 graft. Study Design: Cohort study; Level of evidence, 2. Methods: Sixty-two patients who underwent ACL reconstruction were enrolled prospectively: 31 with an ST4 graft and 31 with an STG graft. The same surgical technique, fixation method, and postoperative protocol were used in both groups. Graft incorporation and ligamentization were evaluated with MRI after 1 year of follow-up. The following parameters were evaluated: signal-to-noise quotient (SNQ), tibial tunnel enlargement, signal intensity at the bone-graft interface, and graft signal according to the Howell scale. The number of participants needed to show that the mean SNQ did not differ between the 2 techniques was 31 in each group (with a 1-sided alpha of 2.5% and a 1-sided beta of 10.0%). The Student t test was used to compare the distribution of continuous secondary endpoints. Results: The mean SNQ was 5.2 ± 4.5 for the STG group and 5.9 ± 3.7 for the ST4 group (P = .5100). The mean tibial tunnel widening was 93.7% ± 51.7% for the STG group versus 80.0% ± 42.9% for the ST4 group (P = .2605). The groups did not differ in signal intensity at the bone-graft interface (P = .7502) or in graft signal according to the Howell scale (P = .4544). Conclusion: At the 1-year postoperative follow-up, incorporation and ligamentization of the STG and ST4 grafts were the same based on MRI analysis. The results were at least as good with the ST4 technique as with the standard STG technique in terms of incorporation and ligamentization.

How to Test the Anterolateral Ligament With Ultrasound

Ultrasonography (US) is a nonirradiating, low-cost, real-time imaging modality that has very good spatial resolution. US can be used to view the anterolateral ligament (ALL) and injuries to the ALL. Several authors have sought to analyze the anterolateral aspect of the knee using US with varying luck. All of them analyzed the ALL statically only. The goal of this Technical Note is to describe in detail the technique that we use to analyze the anterolateral aspect of the knee in patients with an anterior cruciate ligament tear. We use a simple technique that starts by locating the tibial end of the ALL. The lateral inferior genicular artery is a reliable landmark in this context. The analysis is dynamic in addition to being static. To determine if the ALL is injured, we look for a lack of tension on the ALL when the knee is internally rotated and for a Segond fracture. We believe that it is essential to start evaluating the ALL by its tibial end. US analysis of the ALL forms the basis for developing an appropriate “à la carte” treatment for the patients injury.